MIDU: Enabling MIMO Full Duplex Ehsan Aryafar Amir Khojastepour - - PowerPoint PPT Presentation

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MIDU: Enabling MIMO Full Duplex Ehsan Aryafar Amir Khojastepour - - PowerPoint PPT Presentation

Feb 11, 2023 770 likes •1.17k views

MIDU: Enabling MIMO Full Duplex Ehsan Aryafar Amir Khojastepour Karthik Sundaresan Princeton NEC Labs NEC Labs Sampath Rangarajan Mung Chiang NEC Labs Princeton ACM MobiCom 2012 ACM MobiCom 2012 Background Background AP AP p 2 p 1 Current

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SLIDE 1

MIDU: Enabling MIMO Full Duplex

Karthik Sundaresan Amir Khojastepour Ehsan Aryafar NEC Labs Sampath Rangarajan NEC Labs Princeton Mung Chiang

ACM MobiCom 2012

NEC Labs Princeton

ACM MobiCom 2012

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SLIDE 2

Background Background

AP C t i l di h lf d l

p1 p2

AP

  • Current wireless radios are half duplex

Amir Khojastepour NEC Laboratories America

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SLIDE 3

Background Background

AP C t i l di h lf d l

p1 p2

AP

  • Current wireless radios are half duplex
  • Same band Full duplex is hard

Self interference is very high 75 dB for 15 dBm Tx power – Self interference is very high: ≈75 dB for 15 dBm Tx power – Transmitted signal is known  self interference cancellation – Self interference can be significantly reduced by adding a g y y g cancellation circuit: e.g., a cancelling antenna

Amir Khojastepour NEC Laboratories America

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SLIDE 4

Background Background

AP C t i l di h lf d l

p1 p2

AP

  • Current wireless radios are half duplex
  • Same band Full duplex is hard

Self interference is very high 75 dB for 15 dBm Tx power – Self interference is very high: ≈75 dB for 15 dBm Tx power – Self interference can be significantly cancelled by adding a cancellation circuit: e.g., a cancelling antenna

Can full duplex wireless double the capacity?

Amir Khojastepour NEC Laboratories America

slide-5
SLIDE 5

Full Duplex vs. MIMO Full Duplex vs. MIMO

  • Hardware complexity,

performance, size, cost metrics

Amir Khojastepour NEC Laboratories America

slide-6
SLIDE 6

Full Duplex vs. MIMO Full Duplex vs. MIMO

  • Hardware complexity,

performance, size, cost metrics

  • Antenna Conserved (AC): Same
  • Antenna Conserved (AC): Same

# antennas

Amir Khojastepour NEC Laboratories America

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SLIDE 7

Full Duplex vs. MIMO Full Duplex vs. MIMO

  • Hardware complexity,

performance, size, cost metrics

  • Antenna Conserved (AC): Same
  • Antenna Conserved (AC): Same

# antennas

  • RF‐Chain Conserved (RC): Same

# chains

Amir Khojastepour NEC Laboratories America

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SLIDE 8

Full Duplex vs. MIMO Full Duplex vs. MIMO

  • Hardware complexity,

SI loss: 6 dB Ant Correlation: 0.1 performance, size, cost metrics

  • Antenna Conserved (AC): Same

 = 0.01

  • Antenna Conserved (AC): Same

# antennas

  • RF‐Chain Conserved (RC): Same

80 100 nel use)  FD-RC HD FD-AC

# chains

  • Significant FD gains in RC model

40 60 ty (bit/chann

Significant FD gains in RC model

  • Limited FD gains with small #

antennas in AC model higher gains with more antennas

5 10 15 20 20 Capaci

gains with more antennas

Amir Khojastepour NEC Laboratories America

5 10 15 20 Number of Antennas

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SLIDE 9

Full Duplex vs. MIMO Full Duplex vs. MIMO

  • Hardware complexity,

SI loss: 6 dB Ant Correlation: 0.1

 = 0.01

performance, cost metrics

  • Antenna Conserved (AC): Same

80 100 nel use)  FD-RC HD FD-AC

  • Antenna Conserved (AC): Same

# antennas

  • RF‐Chain Conserved (RC): Same

Regions of pronounced full duplex gains in b th RC d AC m d ls

40 60 ty (bit/chann

# chains

  • Significant FD gains in RC model

both RC and AC models

5 10 15 20 20 Capaci

Significant FD gains in RC model

  • Limited FD gains with small #

antennas in AC model high gains with more antennas

5 10 15 20 Number of Antennas

gains with more antennas

Amir Khojastepour NEC Laboratories America

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SLIDE 10

Outline Outline

  • Background

Background i f

  • Design of MIDU
  • Experimental Evaluation
  • Conclusion

Amir Khojastepour NEC Laboratories America

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SLIDE 11

MIDU: MImo full‐DUplex MIDU: MImo full DUplex

  • Symmetric antenna

T1 R1 T'1

placement

1 1 1

d d d d π

Input Signal Input Signal

Amir Khojastepour NEC Laboratories America

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SLIDE 12

MIDU: MImo full‐DUplex MIDU: MImo full DUplex

  • Symmetric antenna

RX Chain

placement

  • 2 level of antenna

R1

  • 2‐level of antenna

cancellation

– Tx cancellation followed by Rx cancellation

T1 T'1

π

Rx cancellation – Proved in theory to have additive gains under imbalanced gains/phase or

R'1

imbalanced gains/phase or imprecise placement

π

Amir Khojastepour

TX Chain

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SLIDE 13

MIDU: MImo full‐DUplex MIDU: MImo full DUplex

  • Symmetric antenna

placement

  • 2 level of antenna

R2 R3

  • 2‐level of antenna

cancellation

– Tx cancellation followed by Rx cancellation

R1

Rx cancellation – Proved in theory to have additive gains under imbalanced gains/phase or

T1 T2 T3 T'1 T'2 T'3

imbalanced gains/phase or imprecise placement

l b l

R'1 R'2

  • Easy scalability to MIMO

Amir Khojastepour NEC Laboratories America

R'3

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SLIDE 14

Implementation Implementation

  • WarpLab implementation

– Narrow‐band 625 KHz – Open space environment – MIDU + MU‐MIMO MIDU + MU MIMO

Virtex‐IV Pro FPGA

NEC Laboratories America Amir Khojastepour

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SLIDE 15

Implementation Implementation

  • WarpLab implementation

– Narrow‐band 625 KHz – Open space environment – MIDU + MU‐MIMO MIDU + MU MIMO

  • Performance metric: SNR or the

di Sh i corresponding Shannon capacity

Virtex‐IV Pro FPGA

NEC Laboratories America Amir Khojastepour

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SLIDE 16

Implementation Implementation

  • WarpLab implementation

– Narrow‐band 625 KHz – Open space environment – MIDU + MU‐MIMO MIDU + MU MIMO

  • Performance metric: SNR or the

di Sh i corresponding Shannon capacity

  • Spectrum analyzer based

Virtex‐IV Pro FPGA

  • Spectrum analyzer based

measurement or the SNR reported by WARP

NEC Laboratories America Amir Khojastepour

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SLIDE 17

Experimental Evaluation Experimental Evaluation

  • Feasibility

– Channel–distance relationship – Stability – Impact on far‐field users

R2 R3

Impact on far field users

  • Cancellation

R1

– Single‐level – 2‐level and MIMO

T1 T2 T3 T'1 T'2 T'3

  • Comparison with MIMO

– Single link Single cell

R'1 R'2

– Single cell

Amir Khojastepour NEC Laboratories America

R'3

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SLIDE 18

Impact of MIDU on ld Far‐Field Users

  • Issue: How does symmetric

y antenna placement impact the far‐field users?

Amir Khojastepour

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SLIDE 19

Impact of MIDU on ld Far‐Field Users

  • Issue: How does symmetric

14 13

y antenna placement impact the far‐field users?

3 4 15 12

TX

1 2 5 6 16 11 9 10 7 8 20 17

<3m>

20 19 18

Amir Khojastepour

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SLIDE 20

Impact of MIDU on ld Far‐Field Users

  • Issue: How does symmetric

y antenna placement impact the far‐field users?

  • Achieved SNR can be up to 4

dB higher/lower

Amir Khojastepour

Inner Circle Outer Circle

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SLIDE 21

Impact of MIDU on ld Far‐Field Users

  • Issue: How does symmetric

y antenna placement impact the far‐field users?

  • Achieved SNR can be up to 4

dB higher/lower I f fi ld t

  • In far‐field antenna

cancellation has very limited effect due to signal scattering (fading) g ( g)

  • Similar results hold for RX

cancellation

Amir Khojastepour

Inner Circle Outer Circle

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SLIDE 22

Experimental Evaluation Experimental Evaluation

  • Feasibility

– Channel–distance relationship – Stability – Impact on far‐field users

R2 R3

Impact on far field users

  • Cancellation

R1

– Single‐level – 2‐level and MIMO

T1 T2 T3 T'1 T'2 T'3

  • Comparison with MIMO

– Single link Single cell

R'1 R'2

– Single cell

Amir Khojastepour NEC Laboratories America

R'3

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SLIDE 23

Cancellation Cancellation

  • Issue: Is 2‐level cancellation

T1 R1 T'1

additive? Is MIDU scalable?

  • Connect the receiver to a

1 1 1

d d

  • Connect the receiver to a

spectrum analyzer d d π

Input Signal Input Signal

Amir Khojastepour NEC Laboratories America

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SLIDE 24

Cancellation Cancellation

  • Issue: Is 2‐level cancellation

additive? Is MIDU scalable?

  • 22

30 dB cancellation on each

  • 22 – 30 dB cancellation on each

level separately

  • Cancellation remains relatively

unchanged with Tx power

Amir Khojastepour NEC Laboratories America

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SLIDE 25

Cancellation Cancellation

  • Issue: Is 2‐level cancellation

RX Chain

additive? Is MIDU scalable?

  • Phase shifter on each path to

R1

Θ

  • Phase shifter on each path to

handle insertion loss and delay

T1 T'1

Θ+π

R'1 TX Chain

Θ+π Θ

Amir Khojastepour NEC Laboratories America

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SLIDE 26

Cancellation Cancellation

  • Issue: Is 2‐level cancellation

additive? Is MIDU scalable?

  • Phase shifter on each path to
  • Phase shifter on each path to

handle insertion loss and delay

  • RX cancellation on top of TX

cancellation is additive

Amir Khojastepour NEC Laboratories America

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SLIDE 27

Cancellation Cancellation

  • Issue: Is 2‐level cancellation

additive? Is MIDU scalable?

  • Phase shifter on each path to
  • Phase shifter on each path to

handle insertion loss and delay

  • RX cancellation on top of TX

cancellation is additive

  • 4 dB decrease in cancellation

for the first added pair, 5 dB with 3 total pairs with 3 total pairs

Amir Khojastepour NEC Laboratories America

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SLIDE 28

Experimental Evaluation Experimental Evaluation

  • Feasibility

– Channel–distance relationship – Stability – Impact on far‐field users

R2 R3

Impact on far field users

  • Cancellation

R1

– Single‐level – 2‐level and MIMO

T1 T2 T3 T'1 T'2 T'3

  • Comparison with MIMO

– Single link Single cell

R'1 R'2

– Single cell

Amir Khojastepour NEC Laboratories America

R'3

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SLIDE 29

Comparison with MIMO Comparison with MIMO

  • Compare MIDU to MU‐MIMO

R

– RF‐Chain conserved model – Multi‐user beamfoming/filtering for MU‐MIMO in each direction UL  DL interference in MIDU

R1 R2 MIDU BS

– UL  DL interference in MIDU

  • Metric: Shannon capacity of the

measured SNR

R5 R6

measured SNR

R3 R4

2m Amir Khojastepour NEC Laboratories America

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SLIDE 30

Comparison with MIMO Comparison with MIMO

  • Compare MIDU to MU‐MIMO

M: #UL Streams N: #DL Streams – RF‐Chain conserved model – Multi‐user beamfoming/filtering for MU‐MIMO in each direction UL  DL interference in MIDU – UL  DL interference in MIDU

  • Full duplex gains diminish as

the number of streams is scaled the number of streams is scaled

Amir Khojastepour NEC Laboratories America

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SLIDE 31

Comparison with MIMO Comparison with MIMO

  • Compare MIDU to MU‐MIMO

3 DL Streams Var UL Streams – RF‐Chain conserved model – Multi‐user beamfoming/filtering for MU‐MIMO in each direction UL  DL interference in MIDU – UL  DL interference in MIDU

  • Full duplex gains diminish as

the number of streams is scaled the number of streams is scaled

  • For maximum full duplex gains,

the number of streams the number of streams between UL and DL should be dis‐proportionate

Amir Khojastepour NEC Laboratories America

slide-32
SLIDE 32

Comparison with MIMO Comparison with MIMO

  • Compare MIDU to MU‐MIMO

3 DL Streams Var UL Streams – RF‐Chain conserved model – Multi‐user beamfoming/filtering for MU‐MIMO in each direction UL  DL interference in MIDU – UL  DL interference in MIDU

  • Full duplex gains diminish as

the number of streams is scaled

Full duplex has great potential in practical single cell MU-MIMO schemes in which the

the number of streams is scaled

  • For maximum full duplex gains,

the number of streams

s ng c M M MO sch m s n wh ch th number of streams is small

the number of streams between UL and DL should be dis‐proportionate

Amir Khojastepour NEC Laboratories America

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SLIDE 33

Related Work Related Work

  • Single‐antenna full duplex

Single antenna full duplex

– M. Knox, “Self‐jamming for full duplex” Tx Signal Tx Output Enhanced Circulator design for full duplex wireless Enhanced Circulator design for full duplex wireless Tx Signal Tx Output Rx Inp t Interference Cancellation Circuit Interference Cancellation Circuit Rx Input

+

Amir Khojastepour NEC Laboratories America

Cancellation Circuit Cancellation Circuit Rx Signal

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SLIDE 34

Related Work Related Work

  • Single‐antenna full duplex

Single antenna full duplex

– M. Knox, “Self‐jamming for full duplex”

  • Asymmetric Antenna cancellation
  • Asymmetric Antenna cancellation

– J. Choi, et. al., “Achieving single channel full duplex”

Amir Khojastepour NEC Laboratories America

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SLIDE 35

Related Work Related Work

  • Single‐antenna full duplex

Single antenna full duplex

– M. Knox, “Self‐jamming for full duplex”

  • Asymmetric Antenna cancellation
  • Asymmetric Antenna cancellation

– J. Choi, et. al., “Achieving single channel full duplex”

  • Analogue cancellation
  • Analogue cancellation

– M. Jain, et. al., “Practical full duplex” – M Durate et al “Full duplex with off‐the‐shelf radios" – M. Durate, et. al., Full duplex with off‐the‐shelf radios

Amir Khojastepour NEC Laboratories America

slide-36
SLIDE 36

Related Work Related Work

  • Single‐antenna full duplex

Single antenna full duplex

– M. Knox, “Self‐jamming for full duplex”

  • Asymmetric Antenna cancellation
  • Asymmetric Antenna cancellation

– J. Choi, et. al., “Achieving single channel full duplex”

  • Analogue cancellation
  • Analogue cancellation

– M. Jain, et. al., “Practical full duplex” – M Durate et al “Full duplex with off‐the‐shelf radios" – M. Durate, et. al., Full duplex with off‐the‐shelf radios Our work presents the design and implementation f th fi t MIMO f ll d l t

Amir Khojastepour NEC Laboratories America

  • f the first MIMO full duplex system
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SLIDE 37

In Summary In Summary

  • Designed and implemented MIDU, the first MIMO full duplex

i l t wireless system

  • Enabled two stages of antenna cancellation with additive gains that

provided as high as 45 dB self interference cancellation provided as high as 45 dB self‐interference cancellation

  • Built a prototype of MIDU with joint operation of 3x3 MIMO + Full

Duplex in practice Duplex in practice

  • Provided guidelines for the design of an efficient MAC for single

cells employing MIDU nodes cells employing MIDU nodes

NEC Labs: http://www.nec‐labs.com/ Princeton EdgeLab: http://scenic.princeton.edu/ Princeton EdgeLab: http://scenic.princeton.edu/

Amir Khojastepour NEC Laboratories America